Electrochemical behaviour of chromium in acid solutions with H2S

The electrochemical behaviour of chromium in acid solutions with hydrogen s ulfide (H2S) was studied by the potentiostatic polarization method and A.C. impedance technique. Results show that H2S can remarkably accelerate both the anodic dissolution and the hydrogen evolution reaction. However, it has almost no influence on the passive state of chromium and cannot cause the breakdown of the passive film of chromium. The Nyquist impedance diagrams o f chromium have been changed in size and shape by H2S. An anodic dissolutio n mechanism for chromium in acid solution with H2S was proposed to explain the obtained results. (C) 1999 Elsevier Science Ltd. All rights reserved.